The present invention relates to a method and apparatus of treating waste utilizing ozone that is produced by passing a stream of air and waste-containing liquid effluent through a cell containing a bed of conductive particles.
It is well known that the basic ozonator comprises a pair of elongated metal electrodes separated by an insulator. When a current of air is passed between electrodes and a high voltage alternating current is applied to the electrodes, ozone is formed. The reaction is expressed by the following electrochemical equation: EQU O.sub.2 +e.sup.- =20+e.sup.- EQU O+O.sub.2 +M=O.sub.3 +M
where e is the initial electron charge generated and M is the available molecules of gas stabilizing the ozone molecule.
In the process, oxygen atoms are formed due to the collision of O.sub.2 molecules with electrons, then some of these atoms attach themselves to the oxygen molecules. The excess energy of the newly formed ozone is carried off by any available molecules of gas (M) stabilizing the ozone molecule. The concentration of ozone in the gas stream is usually 1-2% by weight because of the competing ozone dissociation which destroys the ozone.
The dissociation of oxygen with subsequent formation of ozone may also be brought about by ultraviolet or gamma radiation.
U.S. Pat. No. 2,271,895 discloses an apparatus and method for treating liquids by the use of electric discharges in the presence of a liquid and a gas and/or vapor. The method requires the pre-saturation of the liquid with gas and the subsequent passing of the liquid in a thin film while subjecting it to electric discharge.
U.S. Pat. No. 2,867,573 discloses a method for the production of aqueous liquids having a high oxidizing potential for use in the treatment of waste liquors before they have passed into streams.
U.S. Pat. No. 3,975,247 discloses a process for treating sewage and recovering useful water and solids by passing waste fluid up and down between a plurality of electrode plates. In the process, ozone is generated and utilized for destroying odors and preventing bacterial and fungal growth.
Due to its stability, ozone must be removed from the generating equipment and injected into the stream to be treated with minimum delay. Since it has a low solubility in water it requires an elaborate contacting procedure in the treatment of waste. Ozone further presents a hazard in its production since it is highly poisonous. Additionally, use of ozone in a waste system that is introduced through a secondary source presents a distinct hazard if ozone leakage occurs.